#define _CRT_SECURE_NO_WARNINGS 1
#include<stdio.h>
int main()
{
	int n, a = 1, b = 1, c;
	double sum = 0;
	printf("n:");
	scanf("%d", &n);
	if (n <= 0) {
		return 0;
	}
	for (int i = 1; i <= n; i++)
	{
		sum += 1.0 * a / b;
		c = a;
		a += b;
		b += a;
		b = c;
	}
	printf("sum=%5.2lf", sum);
	return 0;
}